In an ink jet recording method for forming an image by discharging a liquid droplet from a discharge port for deposition on a recording medium represented by paper, technical developments are being continued for improving various performances. Among these, a strong requirement exists for forming a smaller droplet for improving the image quality, and a technology is requested for forming a fine structure constituting an ink flow path or a nozzle with a high precision. For such technology, photolithography is superior in the precision and the simplicity of process, and Japanese Patent Application Laid-Open No. H06-286149 discloses a method of preparing an ink jet recording head by a photolithographic process utilizing a cationic polymerization of a cationic polymerization of an epoxy resin.
A material cured by a cationic polymerization is generally better in the ink resistance in comparison with that obtained by a radical polymerization, and is suitable for use in an ink jet recording head.
On the other hand, for improving the recording head, a larger size of the recording head itself and an increase in a printing width thereof are very effective, and are being investigated in the heads of various types. However a heating process is often employed in the production process, and it is known that a resinous material, employed for preparing a nozzle member, generates a residual stress with an adjacent inorganic material such as a substrate, because of a contraction at curing or a thermal hysteresis. Also in case the nozzle member becomes larger in a thickness or an area, the stress acting on the nozzle pattern becomes larger, often leading to a peeling from the substrate or a crack formation, and a reduction in the stress is therefore a major target.
For reducing the stress in a resin coated film, there are representatively known a method of adding an inorganic material such as a filler thereby reducing a thermal expansion of the resin and a method of adding a material of a high flexibility thereby reducing the elastic modulus of the resin itself. In fact Japanese Patent Application Laid-Open No. H09-234874 discloses a method of employing a filler-containing resin for the nozzle member and molding it by an ablation with an excimer laser. Also EP 0431809 discloses a film coating material in which an organosilane compound is added to an epoxy resin thereby providing flexibility and improving fragility of the resin itself. In a more flexible film, the internal stress itself is estimated to be lower. On the other hand, U.S. Pat. No. 6,312,085 discloses a method of preparing an ink jet head by executing a patterning with a radical photopolymerization and forming/curing a siloxane bond by a heat treatment.
As to the formation of a nozzle member for a recording head capable of achieving an increase in the printing width, Japanese Patent Application Laid-Open No. H09-234874 discloses a method of employing a filler-containing resin as a nozzle member and molding it by an ablation with an excimer laser. Such material, however, may be disadvantageous in productivity and cost, in comparison with an ordinary photolithography utilizing a pattern exposure and a development. Also the material disclosed in EP 0431809 is not intended for a fine structure such as an ink jet recording head, and involves, in patterning process, drawbacks of a thickness loss and a dissolution of the coated film, a pattern deformation and an insufficient resolution. On the other hand, the method disclosed in U.S. Pat. No. 6,312,085 may not provide an alkali resistance because a crosslinked structure is formed by a radical polymerization (methacryloxy group), so that the ink resistance is insufficient in certain types of ink.